1. Field of the Invention
This invention relates to a process for producing eggs with low cholesterol level, and in particular, to a process for producing eggs with low cholesterol level by adding fermented red mold rice to hens diet so as to reduce cholesterol level of eggs.
2. Description of the Prior Art
The relationship between cholesterol and atherosclerosis has long been concerned. Plasma total cholesterol and low-density lipoprotein (LDL) are closely related to atherosclerosis, and excessive concentration of these two materials may lead to coronary artery disease or cause death. Ordinary chicken eggs provide protein, vitamins, and lipids which contains high level cholesterol. Thus, eggs are considered as a high cholesterol food. America Heart Association recommended that the cholesterol take-up for each person should be limited within 300 mg each day, and the whole egg yolk take-up should be limited to 3–4 per week. People are paying more attention to health, thus lowering consumption of high cholesterol food. Since cholesterol in eggs accounts for more than 50% of daily take-up, consumption of egg can hardly increase. Therefore, low cholesterol eggs can not only be beneficial to the public's health, but also bears business advantage.
Egg cholesterol is first biosynthesized in the liver of laying hens and secreted into the plasma in the form of very low density lipoproteins (VLDL). VLDL are then transported to the ovary where they are bound and taken up by growing chicken oocytes via receptor-mediated endocytosis. Egg cholesterol has been shown to vary with species of bird, breed or strain, as well as age of fowl.
Egg cholesterol content can be altered by (1) genetic selection, such as upward direction method or selecting hen that produce low cholesterol eggs; (2) diet alteration, such as adding dietary fiber, sterol, saturated and polyunsaturated fatty acid, cupric sulfate pentahydrate, protein and essential amino acids, chia, or red microalga to laying hens feed; (3) using hypocholesterolemic agent, such as adding probucol, dichloroacetate, atorvastatin, lovastatin, simvastatin or tocotrienols to laying hens feed to regulate egg yolk cholesterol level. Of all the methods mentioned above, lovastatin (monacolin K) showed different result in lowering cholesterol level in eggs.
As far as reducing egg cholesterol concentration was concerned, Elkin and Rogler suggested that addition of 0.2407% lovastatin in feed for 9 days could decrease the amount of cholesterol by 13%. Elkin and Yan pointed out that addition of 0.03% or 0.06% lovastatin could lower egg cholesterol concentration by 4% or 7% (hens of 18 weeks old, and feed for 5 weeks). Mori et al. pointed out that addition of 0.0005% or 0.0015% lovastatin could lower egg cholesterol concentration by 7.5% or 12.7% (hens of 30 weeks old, and feed for 12 weeks). On the other hand, Luhman et al. argued that addition of 0.0035% lovastatin showed no significant decrease in egg cholesterol concentration (hens of 69 weeks old, feed for 5 weeks), and the lovastatin used would remain in hen liver. Sim and Bragg believed that the cholesterol concentration in serum should be reduced prior to the reduction of yolk cholesterol concentration. Therefore, reducing serum cholesterol by applying drugs seems to be the best approach to reduce yolk cholesterol. However, whether there is any drug residue remained in eggs also need to be considered.
Monascus species has been widely used on diet and folk remedy for thousand years in Asia. Secondary metabolites produced from Monascus species include: (1) pigment group; (2) anti-hypercholesterolemic agent such as monacolin K; (3) antioxidant ingredient. Endo discovered the more active methylated form of compactin known as monacolin K (lovastatin) in broths of Monascus ruber. Monacolin K may inhibit the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase in cholesterol biosynthesis. In fact, Monascus species has been proved to inhibit cholesterol biosynthesis. Furthermore, some researches showed that atherosclerosis is not only correlated to cholesterol and LDL in blood, but also correlated to the oxidation of LDL. Chen et al. pointed out that antioxidant ability and cardiovascular diseases were closely related. As a matter of fact, production of monacolin K by Monascus species has been used as a functional dietary supplement to reduce cholesterol level in human body. To our knowledge, the effect of red mold rice on eggs has yet to be investigated in previous studies.
Taiwanese Patent Application No. 396022 discloses the addition of tea polyphenlol from extract or residue of green tea, black tea or oolong tea into hens feeds, whereby the eggs from the fowl have a reduced crude fat content, a reduced peroxide content, an enhanced Haugh unit value, an enhanced degree of transparency of egg white, an enhanced foam-forming ability, a pure white color when the eggs are beaten to form a foam and a pure white color egg white when the eggs are cooked.
In views of the above-described researches associated to inhibition of cholesterol biosynthesis by using metabolite of Monascus species, the applicant keeps on carving unflaggingly to develop a process for producing eggs with low cholesterol level according to the present invention through wholehearted experience and research.